In recent years, in the field of magnetic recording, with the improvement in performance of recording and reproducing equipment such as digitalization, scale reduction, and elongation of time for use, development of a highly dense magnetic recording medium suitable therefor is actively taking place. Recently, a metal thin film type magnetic recording medium, which is extremely advantageous for a short wave length recording, is put into practical use in lieu of an application type magnetic recording medium.
However, since a magnetic layer of a metal thin film type magnetic recording medium has an extremely good surface property, i.e. a small roughness on the surface, it contacts with a magnetic head in broader area, and, as the result, it is liable to be abraded by receiving a great friction force while being in a rapid sliding movement with the magnetic head during a process of recording/reproducing signals. Abrasion of the magnetic layer greatly affects the running durability, the still durability, or the like, so that reduction of the abrasion of the magnetic layer is a great object in the research and development of a metal thin film type magnetic recording medium.
Therefore, an attempt is made to reduce the abrasion by disposing a lubricant layer on a magnetic layer surface to improve the running durability and the still durability. In the case where the lubricant layer is disposed, the lubricant layer on the magnetic layer surface is requested to exhibit a lubricating property with a thickness as small as several nanometers in order to prevent the output reduction caused by a spacing loss between the magnetic recording medium and the magnetic head as much as possible for achieving a high output. Accordingly, use of a fluorine-based compound exhibiting an excellent lubricating property is widely studied and use of various compounds is proposed.
For example, use of a fluorine-containing long chain carboxylic acid ester (See Japanese Laid-open Patent Publication No. 62-46431/1987) represented by the following chemical formula (X): EQU C.sub.18 H.sub.35 OCOC.sub.9 F.sub.17 (X)
or a fluorine-containing carboxylic acid monoester having a carboxyl group (See Japanese Laid-open Patent Publication No. 61-107529/1986) represented by the following chemical formula (Y): ##STR1##
or the like, is proposed.
However, the request concerning the improvement of the performance of the magnetic recording medium is demanding, and it is difficult to obtain a sufficient lubricity with the aforementioned conventional lubricants, so that a further improvement of the running durability and the still durability for the magnetic recording medium is desired.